Anchoring reinforcing cables or braids in well packers



H. L. SANDLIN Filed May 20, 1957 INVENTOR. Herman L. Sendlin,

BY i

FIG.

Kul# 9.13.6'... .4, A7#

FIG. 4.

ATTORNEY.

Oct. l0, 1961 ANCHORING REINFORCING CABLES OR BRAIDS IN WELL PACKERSUnite States This invention relates to the connection of interfttingmetallic members and more particularly to the interconnection ofstrain-bearing members of a well packer.

In connection with the construction of well packers, it has been thepractice to secure flexible packing members, such as cables or braids,to a pair of end plates by a clamping arrangement wherein the ilexiblebraid or cable is clamped against a rough, generally sharp-toothedsurface on each end plate so that the teeth bite into the cable or braidand effectively lock thereto, Another arrangement that has beensuccessful with cable reinforced packers has been to lace a cable backand forth between the end plates through bores drilled into the platesnear the edges thereof. While both of the above-described arrangementshave advantages, there are certain objectionable disadvantages attendantto their use. For example, in connection with lacing a cable back andforth between end plates, it has been found diflicult, if notimpossible, to make the various cable loops of the same length.Therefore, the various sections of the cable will not carry the sameload and will tend to break prematurely. With the tapered wedgearrangement the strength of the connection is not particularly great andmany packer failures have been encountered.

Manifestly, it should be possible to anchor individual lengths of cableor a braid into recesses drilled or otherwise formed in the end plates.However, in the past this arrangement has not been particularlysuccessful. Babbitt metal or Zinc has been used to anchor cables inbores, but Babbittmetal must be applied at such high temperatures (inthe vicinity of 1l00 F.) that the heat causes the cables to lose theirtemper and, hence, to break easily under subsequent tension and flexing.While zinc may be applied at low temperatures, it lacks holdingstrengthy and inevitably fails under relatively light loads. The use ofgranulated particles to lock cables to a bore as described in U.S.Patents No. 1,827,297 to C. R. Moore, No. 2,149,209 to D. P. Dickie etal., and No. 2,038,535 to O. W. Bernizer, is precluded because of theimpossibility of compressing the end plates of well packers as requiredby the teachings of the aforementioned patents.

Accordingly, it is one object of this invention to provide an improvedmethod for interconnecting two members that effects a junction of greatstrength and that may be applied at low temperatures.

Another object is to provide a connection for intertting members thatwill not be eiected by temperatures in the vicinity of 350 F.

Still another object is to provide a cable-reinforced well packerwherein the cables may be madel to carry substantially the same loadwhen the packer is sealing oli a section of a borehole.

Still another object is to provide a connection for the llexiblemetallic members of a well packer that will not ice adversely effect thestrength of the flexible metallic members.

Other objects and features will become apparent upon consideration ofthe following detailed description of the invention when taken inconnection with the accompanying drawings, wherein:

FIG. l is a front elevation, partially in cross-section, of a typicalwell packer that may be used in connection with this invention;

FIG. 2 is an enlarged sectional view of a portion of the well packerillustrated in FIG. l showing certain of the component parts o-f thecable anchor in greater detail;

FIG. 3 is a cross-sectional view taken along the line 3 3 of FiG. 2;

FIG. 4 is a sectional view somewhat similar to FIG. 1 illustratinganother embodiment particularly adapted for anchoring a metallic sheath;and

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 4.

The well packer illustrated in FIG. l is in many respects similar towell packers that have been in use in the oil industry for many years.It is -to be understood that this particular well packer is shown forillustrative purposes only and that many other types of well packers canbe utilized in accordance with the teachings of this invention, such asthe packers illustrated in Patent 2,828,823, for Reinforced IniiatablePackers, by W. D. lvlounce and assigned to the assignee of thisinvention. The packer shown in FIG. 1 includes a well pipe 1 to which issecured an end plate 3, the end plate threadingly engaging well pipe 1and being secured against rotation by a set screw 5. An O-ring sealingmember 6 is provided for the purpose of obtaining a fluid-tight sealagainst the relatively high pressures which must Vbe exerted to inatethe packer. The lower end of end plate 3 is provided with a plurality ofrecesses or bores 10 which are tapped in order to provide a roughsurface in each recess for purposes to be described below.

A second end plate 21 is adapted to slide on the outer surface of wellpipe 1 below end plate 3.' End plate 21` is provided with an O-ringsealing member 25, and has a plurality of tapped recesses or boressimilar to recesses l0. A plurality of cable members 9 (each comprisinga plurality of spirally wound wires, as shown most perspicuously in FIG.2) of approximately the same length interconnect end plates 3 and 21,the ends of the cable members being inserted in the recesses or lbores10 and 23. The cable ends are secured to the recesses by apottingcomposition 11 Iwhich will be described in greater detail below. Thecables 9 act as a support upon which is formed a sheath or seal ofrubber or rubber-like material 7. A fluid passage-way 13 extendingthrough well pipe 1 opens to the exterior of the well pipe within thesheath formed by cables 9 and rubber-like composition 7 so that uidpressure may be exerted on the interior of the sheath arrangement'toinflate the packer. Manifestly, the lower end plate 21 will slide up anddown on the well pipe in accordance Iwith the pressure exerted on theinterior surface of sheathr 7.

The cable ends are secured to the end plates 3 by lirst lling therecesses in the end plates with a particular type of slurry, thecomposition of which is described below, after tapping the interior ofrecess 10 to insure a rough surface therein. The cables are inserted inthe recesses, and the end plates and cables are thereupon placed withinan oven and baked for a period of at least 2 hours at a temperature ofat least 200 C. Preferably, the potting slurry is allowed to air dry for2 hours before the baking operation but this is not absolutelynecessary. Thereafter, the rubber or rubber-like sheath 7 is formed onthe cables.

The potting slurry above described comprises a resinous material,preferably an exoxy resin, a granular filler and a heat responsivepolymerizing (or hardening) agent for the resin. In order to addviscosity to the mixture, silicon dioxide may be added thereto althoughthis has been found to be not absolutely necessary.

Epoxy resins have been found to be particularly desirable forapplication in this invention as the molecules thereof have the propertyof adhering to the molecules of other materials to an extent greaterthan any other known resin. The granular ller should be of at least thesame hardness as the hardness of the materials of the members which areto be joined together. If the granular filler is of a materialsubstantially harder than the members to be joined together, it may notbe necessary to roughen the surface of the recess. However, for wellpacker applications, a rough-surfaced recess is preferred. Suitablellers for this application have been found to be earborundum, corundum,and aluminum oxide (A1203).

The polymerizing or hardening agent should have the followingproperties: (1) it must form a slurry with the other constituentsdescribed above; (2) the slurry formed therewith should not harden byitself at ordinary room temperatures for a period of at least 2 hours;(3) it should be heat-responsive, i.e., the hardening of the slurrycontaining the agent should be substantially accelerated by theapplication of heat; and (4) the slurry formed therewith should have aheat distortion point, when hardened, above the curing temperature ofrubber (350 F.). Suitable curing or hardening agents have been found tobe chlorendic anhydride, pyrornellitic dianhydride, and a mixture, 60%of m-phenylenediamine and 40% of 4,4methylene dianiline. Suitableslurries for use with the present invention have been found to comprise:

100 parts by weight of resin 40-80 parts by weight of a granular filler20-45 parts by Weight of the hardening agent A very specific compositionthat has been found to be particularly satisfactory is the following:

100 parts by weight of resin 60 parts by Weight of carborundum 2O partsby weight of pyromellitic dianhydride The granular fillers describedabove should be 20-40 mesh in size or approximately 2-4 mils indiameter. It is believed that the granular particles interlock with eachother and with the surfaces of the members to be joined to effectivelyform a bond between the members themselves. Utilizing steel cableshaving a diameter of inch anchored to steel end plates, and subjectingthe cables to gradually increasing tension, it has been found that thecables themselves will break before the bond between the cables and theend plates is alected.

It should be noted that the invention is not to be limited to theabove-described packer connection utilizing cable means. In FIG. 4 thereis illustrated a connection particularly adapted for use with braidedsocks such as described in the aforementioned patent application, SerialNo. 520,424. In this construction the end plate comprises an innersection l5 and an outer section 16 screw threaded to form the recess a.The braided sheath 17 is inserted into the annular recess formed by thetwo sections 0f the end plate. The potting composition utilized inconnection with the apparatus shown in FIGS. 4 and 5 is the same as thatdescribed in connection with the embodiment shown and described withreference to FIGS. l, 2 and 3. With the exception of the use of thebraided sheath and the particular construction of the annular recess10a, the well packer is the same as that shown in HG. 1.

Although the embodiments disclosed in the preceding specification arepreferred, other modifications will be apparent to those skilled in theart which do not depart from the broadest aspects of the scope of theinvention.

What is claimed is:

l. Apparatus for end-connecting rough-surfaced, metallic reinforcingmeans of a well packer, comprising: an annular end plate adapted to taround a drill pipe; recess means in the end plate adapted to receivethe reinforcing means; the ratio of the diameter of the recess means tothe diameter of the reinforcing means being between 1.2 to l and 1.35 tol; and potting means between the reinforcing means and the end platecomprising parts by weight of an epoxy resin, 40 to 80 parts by weightof a granular filler for said resin selected from the group consistingof carborundum, corundum, and A1203, and 20 to 4S parts by weight of aheat responsive hardening agent selected from the group consisting ofchlorendic anhydride, pyromellitic dianhydride, and a compound formed bya mixture of 60% of m-phenylenediamine and 40% of 4,4methylenedianiline.

2. Apparatus for connecting together the ends of Well packer cables,comprising: an annular plate; a plurality of recesses in the platecorresponding in number to the number of cables to be connected; theratio of the diameter of each recess to the diameter of the cable to beinserted therein being between 1.2 to l and 1.35 to l; and potting meansin each recess for securing the cables to the plate comprising 100 partsby weight of an epoxy resin, 40 to 80 parts by weight of a granular llerfor said resin selected from the group consisting of carborundum,corundum, and A1203, and 20 to 45 parts by weight of a heat responsivehardening agent selected from the group consisting of chlorendicanhydride, pyromellitic dianhydride, and a compound formed by a mixtureof 60% of m-phenylenediamine and 40% of 4,4methylene dianiline.

3. A method of connecting a cable to a member compn'sing the followingsteps: drilling a rough-surfaced recess in said member having a diameternot more than 1.35 times the outer diameter of the cable; forming apotting material by mixing 100 parts by weight of an epoxy resin withbetween 20 to 45 parts by weight of a heat responsive hardening agentselected from the group consisting of chlorendic anhydride, pyromelliticdianhydride, and the compound formed by a mixture of 60% ofm-phenylenediamine and 40% of 4,4'methylene dianiline, and with 40 to 80parts by weight of a granular filler selected from the group consistingof carborundum and corundum; inserting the potting material into saidrecess with the cable so that said potting material lills the spacebetween the cable and the surface of the recess; and heating said cablebore and potting material to a temperature of 350 F. for at least 2hours.

4. A method of connecting a cable to a member having a bore forreceiving said cable comprising the following steps: roughening thesurfaces of the bore and the cable; forming a potting material by mixing100 parts by weight of an epoxy resin with 40 to 8O parts by Weight of agranular ller selected from the group consisting of carborundum andcorundum, and between 20 to 45 parts by weight of a heat responsivehardening agent selected from the group consisting of chlorendicanhydride, pyromellitic dianhydride, and the compound formed by amixture of 60% of m-phenylenediarnine and 40% of 4,4- methylenedianiline; inserting the potting material and the cable into the bore sothat the potting material fills the space in the bore around the cable;and heating the 5 cable, bore, and potting material to a temperature ofat 2,643,722 least 350 F. for atleast 2 hours. 2,768,090 2,828,823References Cited in the file of this patent UNITED STATES PATENTS 51,189,235 Brown July 4, 1916 571,662 1,283,574 Schuster et a1 Nov. 5,1918 1,827,297 Moore Oct. 13, 1931 2,357,733 Guderian Sept. 5, 19442,379,990 Rembert :my 1o, 1945 10 pages ros-9 9. '1 2,528,933 Wiles Nov.7, 1950 2,561,351 Fentress July 24, 1951 6 Lynes .Tune 20, 1953 WittcoffOct. 23, 1956 Mounce Apr. 1, 1958 FOREIGN PATENTS Canada n Mar. 3, 1959OTHER REFERENCES Industrial Engineering Chemistry, July 1957, vol. 49,

Industrial and Engineering Chemistry, October 1956, vol. 48, No. 10(Flame-and-JHeat Resistant Epoxy Resins).

